1. Field of the Invention
The instant invention is directed to blow molded articles and a process for forming them. More specifically, the instant invention is directed to polybutylene terephthalate blow molded articles and a process for forming them. Still more specifically, the instant invention is directed to polybutylene terephthalate injection blow molded articles and the process for forming them.
2. Background of the Invention
Work in the polyester field has accelerated in recent years. Among the more dramatic developments in polyester research has been the discovery that polybutylene terephthalate may be successfully molded. Furthermore, these polybutylene terephthalate molding resins have been found to be surprisingly superior to polyethylene terephthalate in many important molding applications. This has led to extensive development work in the area of polybutylene terephthalate injection molded articles and processes for forming them. As a result of these developments, it has been found the polybutylene terephthalate molding resins, which were first disclosed, along with polyethylene terephthalate, in U.S. Pat. No. 2,465,319 to Winfield and Dickson, solve many processing problems long associated with polyethylene terephthalate and believed, by those skilled in the art, to be equally associated with all polyalkylene terephthalate.
Although polybutylene terephthalate resins have been found to possess excellent properties as an injection molded resin, it was heretofore limited to this molding procedure. Because of the relatively low viscosity of polybutylene terephthalate melts, a prime market for polybutylene terephthalate, as blow molding resins, has not been exploited. This market is large and continues to grow. It includes such blow molded articles as containers, bottles and the like. Especially important in this market is blow molded bottles designed to withstand extensive pressures, i.e., bottles containing aerosol fluids. In the past polybutylene terephthalate parisons, because of their relatively low viscosity, did not retain their shape for the time necessary to be enclosed within the blow mold. Furthermore, even in those cases when satisfactory parisons were formed, the resultant blow molded articles, i.e., blow molded bottles, did not possess sufficient strength to meet the requirements of the marketplace.